Air cushion method and apparatus for supporting moving film sheets



Nov. 9, 1965 D. J. BRICKLE ETAL 3,215,638

AIR CUSHION METHOD AND APPARATUS FOR 2 Sheets-Sheet 1 Filed Oct. 23, 1962 R E mun mw M mmm w L w mm M OR g M a 3 m. Q Q Q UN\ u 0E 1965 D. J. BRICKLE ETAL 3,216,533

AIR CUSHION METHOD AND APPARATUS FOR SUPPORTING MOVING FILM SHEETS Filed Oct. 23, 1962 2 Sheets-Sheet 2 DONALD J. BRICK LE FRANK Le BOUTILLIER INVENTOR. m/zew/ v\ FIG.2

United States Patent OfiFice 3,216,638 AIR CUSHION IVIETHOI) AND APPARATUS FOR SUPPORTING MOVING FILM SHEETS Donald J. Brickle, Clifton Springs, and Frank Le Boutillier, Canandaigua, N .Y., assignors to National Distillers and Chemical Corporation, New York, N.Y., a corporation of Virginia Filed Oct. 23, 1962, Ser. No. 232,557 2 Claims. (Cl. 226-97) The present invention relates to a method and means for supporting a moving web of a sheeted material. More particularly it relates to a stationary support element providing an air cushion adapted to support a web drawn over such element under tension. The invention relates especially to a method and means adapted to handle sheeted materials which have been coated or treated with liquid or other coating materials and require drying or setting time prior to contact with moving or stationary surfaces of any kind.

Substantially non-porous sheeted materials, including paper, films of thermoplastic materials, and other equivalent compositions, frequently are treated or coated with a variety of substances. Such treatment may include the application of waterproof coatings, printers ink, or other we coating materials. Frequently, it is desirable to coat or treat both surfaces of the sheet or web simultaneously.

In such coating or treating operations, it is customary to pass the coated material through a drying or setting 'zone of substantial length, wherein the web of material is age or alfect the coating or to interfere with effective treatment. To accomplish this result, the web must be freely suspended over relatively long vertical or horizontal distances, at considerable cost for the vertical or horizontal space required.

It is an object of the present invention to provide a method and means whereby the space required for handling films, coated or treated in any fashion, requiring drying and/or setting of a coating or treating material, may be reduced considerably. It is also an object of the present invention to provide a method and means to permit a change in direction of a moving film without contact with stationary or moving solid surfaces. It is a further object of the invention to provide a method and means for supporting a film web on a cushion of low pressure high velocity air during movement of the web through a directional change of the web travel path.

The invention and its objects may be more fully understood from the following description, when it is read with reference to the accompanying drawings, in which:

FIGURE 1 is a schematic showing of a typical application of the invention to a system for coating a web of sheeted material and for drying the coating applied; and

FIGURE 2 is an isometric View, with parts broken away, of an air cushion unit of the character contemplated by the present invention.

Referring to FIGURE 1, the numeral 1 designates a film web, such as of a thermoplastic material derived by extrusion. The numerals 2, 3, 4 and 5 designate a system of rolls representative generally of conventional means for applying a coating material to both sides of the web, simultaneously. The numerals 6 and 6a, 7 and 7a, 8 and 8a, and 9 and 9a designate representative means for applying air to the respective surfaces of the web, whereby to dry or set the coating material on the web and/or remove a solvent therefor.

As should be evident, it is assumed that the film Web coating is not completely dry until it emerges from the drying zone encompassed by the dryer means 9 and 9a. Between this zone and the coating rolls it is essential that 3,216,538 Patented Nov. 9, 1965 the film be maintained free of contact with any surface likely to disturb the coating applied, or itself to develop deposits of such coating.

According to the present invention the film travel path may be collapsed or telescoped by means such as indicated by the numerals ll 11 and 12. In a conventional system a collapsed or telescoped system would require that the web be passed over a series of rollers. In the system illustrated the web is passed over a series of air cushions provided by the elements 10, 11 and 12.

Each of the contemplated elements comprises a housing, respectively designated in FIGURE 1 by the numerals 10a, 11a and 12a connected to a blower 13 as by ducts 10b, 11b and 13b, and a manifold 14. If desired, each housing may be supplied by a separate blower and supply line connection.

In FIGURE 1, the numerals 16, 15 and 18 respectively designate an enlargement of the ducts 12b, 11b, and 10b. The particular form of the duct work involved is more particularly shown in FIGURE 2, as is the nature of the housings 10a, 11a and 12a.

Referring then to FIGURE 2, the device as designated in FIGURE 1 by any of the numerals 1t), 11 or 12 consists of a housing portion such as designated, in this drawing, by the numeral 20. This housing is an elongated member having a longitudinal dimension slightly greater than the film web intended to pass over it.

The housing has a rim portion 21 and sidewall portions 22 and 23, the sidewalls being connected by endwalls, such as designated by the numeral 24. The endwalls, sidewalls, and rim thus form an enclosed space open at the top and bottom. The side walls are divergent and/or shaped in the manner shown for the housings 10 and 11 of FIG- URE 1, but may be altered to provide a housing Wall conformation as shown in FIGURE 1 for the housing 12 as later set forth.

As shown by FIGURE 2, the ducts, such as the duct 10b of FIGURE 1, are shaped to match the rectangular opening of the housing rim. Thus in FIGURE 2, the duct 20b is shaped divergently to conform with the rim portion 21, providing a flared connection between the housing 20 and the duct 20b. This flared portion is designated by the numeral 20c, and in FIGURE 1 by the corresponding numeral 18. The object of such expanded or flared con nection between duct and housing is to provide a substantially nonturbulent, smooth flow of air into the housing 20, at low pressure.

The equiangular relationship of the sidewall portions 22 and 23 is adjusted to provide a circular distance between their free ends which is slightly more than 180, and centered between the ends. In a housing unit such as 12 of FIGURE 1, this distance would be adjusted to encompass slightly more than As shown in FIGURE 2, the sidewalls 22 and 23 are connected by means of an arcuately formed perforate wall member encompassing a circular angle slightly greater than Also, as shown, preferably it is formed from a sheet of flattened, expanded metal. It may be formed by any perforate, rigid, but deformable sheet material, and some of the advantages, according to the present invention, may be retained. In this respect, the primary consideration is to minimize the pressure drop between the interior and exterior of the housing of low pressure air supplied thereto.

Over the perforate metal sheet is applied a fabric cover 26. This cover is formed by a coarse, highly air permeable layer of a sheeted material such as muslin. Other highly air permeable porous materials, whether woven or felted, may also be employed. The preferred materials are those which permit air to pass through the cover in relatively large volume with relatively low pressure drop.

In operation, a film web is threaded through the system in the manner shown by FIGURE 1. Tension is applied to the Web longitudinally thereof as by conventional nip rolls, disposed beyond the outlet of the dryer elements9 and 9a, and rotated at a rate such as to cause the film travel to be resisted slightly by the rolls 2 and 4, or by other conventional means ahead of these rolls. A typical means disposed ahead of rolls 2 and 4 would be a weighted or spring tensioned dancer roll. Neither the nip rolls nor such dancer rolls are shown, as these expedients are Well known in the art.

Having threaded the film web through the system as shown, the blower 13 is started, and the web is moved along the travel path provided. The rate of air flow is adjusted, either by dampers or by the blower speed, to provide a discharge volume sufficient to raise the Web from contact with the covered sections of the housings 10, 11 and 12. This rate and volume will vary depending upon the weight of the web and the tension applied thereto. Adjustment, however, is obtained simply by visual observation.

With the web in motion and supported on air cushions in each area of directional change, the coating or treating process may be started. Both sides of the web may be processed at the same time, as between the coating step and emergence of the dry webfrom the final dryer no portion of the treated web surfaces will come in contact with fixed or moving support surfaces. In addition to providing support and direction to the web as it moves over the cover surfaces, the air cushion support supplements the action of the dryer means specifically provided. If desired, the air supplied to the housings 10, 11 and 12 may also be heated.

What is claimed is:

1. In a system for transporting a continuous web of sheet material through a treatment zone in which the direction of web travel is changed angularly, an apparatus for supporting said web out of contact with solid surfaces at a point at which the direction of web travel is changed, said apparatus comprising (a) an elongated housing having a pair of side walls tapering outwardly from the bottom to the top of said housing, the upper surfaces of said side walls extending for distances slightly greater than the width of said web, and end walls connecting said side walls and defining an outwardly flared zone within the housing;

(b) an air supply conduit connected to the bottom of said housing and communicating with the smaller end of the outwardly flared zone thereof for conveying air under low pressure into the same;

(c) an arcuately shaped, substantially rigid perforated wall member encompassing a circular angle slightly greater than 180 and produced from deformable sheet material, the extremities thereof being secured to the side walls of said housing and having a length substantially corresponding to the lengths of the upper surfaces of said side walls, said arcuate member defining a chamber open at its ends and communicating with the larger end of the outwardly flared zone within said housing; and

(d) a sheet of porous, air-permeable fabric mounted on the periphery of said arcuate member and through which a smooth, low pressure flow of air directed from said housing may pass, thereby providing an arcuate air cushion for supporting said web as its direction of travel is angularly varied.

2. The apparatus as defined in claim 1, in which said sheet of porous, air-permeable fabric is constituted of a woven muslin fabric.

References Cited by the Examiner UNITED STATES PATENTS ROBERT B. REEVES, Primary Examiner.

ANDRES H. NIELSEN, SAMUEL F. COLEMAN,

Examiners. 

1. IN A SYSTEM FOR TRANSPORTING A CONTINUOUS WEB OF SHEET MATERIAL THROUGH A TREATMENT ZONE IN WHICH THE DIRECTION OF WEB TRAVEL IS CHANGED ANGULARLY, AN APPARATUS FOR SUPPORTING SAID WEB OUT OF CONTACT WITH SOLID SURFACES AT A POINT AT WHICH THE DIRECTION OF WEB TRAVEL IS CHANGED, SAID APPARATUS COMPRISING (A) AN ELONGATED HOUSING HAVING A PAIR OF SIDE WALLS TAPERING OUTWARDLY FROM THE BOTTOM TO THE TOP OF SAID HOUSING, THE UPPER SURFACES OF SAID SIDE WALLS EXTENDING FOR DISTANCES SLIGHTLY GREATER THAN THE WIDTH OF SAID WEB, AND END WALLS CONNECTING SAID SIDE WALLS AND DEFINING AN OUTWARDLY FLARED ZONE WITHIN THE HOUSING; (B) AN AIR SUPPLY CONDUIT CONNECTED TO THE BOTTOM OF SAID HOUSING AND COMMUNICATING WITH THE SMALLER END OF THE OUTWARDLY FLARED ZONE THEREOF FOR CONVEYING AIR UNDER LOW PRESSURE INTO THE SAME; (C) AN ARCUATELY SHAPED, SUBSTANTIALLY RIGID PERFORATED WALL MEMBER ENCOMPASSING A CIRCULAR ANGLE SLIGHTLY GREATER THAN 180* AND PRODUCED FROM DEFORMABLE SHEET MATERIAL, THE EXTREMITIES THEREOF BEING SECURED TO THE SIDE WALLS OF SAID HOUSING AND HAVING A LENGTH SUBSTANTIALLY CORRESPONDING TO THE LENGTHS OF THE UPPER SURFACES OF SAID SIDE WALLS, SAID ARCUATE MEMBER DEFINING A CHAMBER OPEN AT ITS ENDS AND COMMUNICATING WITH THE LARGER END OF THE OUTWARDLY FLARED ZONE WITHIN SAID HOUSING; AND (D) A SHEET OF POROUS, AIR-PERMEABLE FABRIC MOUNTED ON THE PERIPHERY OF SAID ARCUATE MEMBER AND THROUGH WHICH A SMOOTH, LOW PRESSURE FLOW OF AIR DIRECTED FROM SAID HOUSING MAY PASS, THEREBY PROVIDING AN ARCUATE AIR CUSHION FOR SUPPORTING SAID WEB AS ITS DIRECTION OF TRAVEL IS ANGULARLY VARIED. 